First choice:
Hardware.

Second choice:
My wife's favorite - I don't know if this would be inexpensive in the US, but it is around here:

In the begining of the season (or many seasons), order a great quantity of very elegant custom made plates with a nice photo of a cat and the name of the club/organization printed on it.

The plates are all the same, but for each race, wooden supports engraved with the name of the race and position are ordered and distributed with the plates as prizes.

If you manage to win enough races, you will get a complete set and can invite your friends to have dinner in your trophies!

This helped convince wifes to participate and, once they get the first plate, to keep coming. It helps to give a tropy to each participant in the first race...

For the next season, you change the size of the plate, until you run out of sizes (probably four years) then you change the photo and start again.

Cheers